1. Field of the Invention
The present invention pertains to a catalyst which is particularly suitable to effect hydroprocessing of heavy hydrocarbon feeds. Although the catalyst is suitable for application in fixed bed processes, it is particularly suitable for application in moving or ebullated bed processes. The present invention also pertains to a process for hydroprocessing hydrocarbon feeds with said catalyst.
2. Prior Art
One of the steps in the preparation of ready-for-use products from heavy hydrocarbon oil fractions is hydroprocessing to effect the complete or partial removal of impurities. Heavy feedstocks, such as feeds based on atmospheric residual oils, vacuum residual oils, tar sand oils, and shale oils generally contain organic sulfur compounds and metallic components. These impurities can be removed by contacting the feedstock with a hydroprocessing catalyst at elevated temperature and pressure in the presence of hydrogen. This will cause the organic sulfur compound to be converted to H2S, while the metals precipitate on the catalyst particles. The catalysts which are to effect this combined hydrodesulfurization and hydrodemetallization have to satisfy quite stringent requirements. On the one hand, the hydrodesulfurization and hydrodemetallization activity of the catalyst should be high, while on the other, the catalyst should have a long life.
Additionally, the use of non-fixed bed processes, such as moving bed processes and ebullated bed processes, is becoming increasingly important in the hydroprocessing of heavy hydrocarbon feedstocks. Non-fixed bed processes have the advantage that it is not necessary to replace the complete catalyst inventory at the same time. Additionally, the contamination of the catalyst inventory with contaminant metals will be more homogeneous. However, the use of a catalyst in a non-fixed bed application places additional requirements on the properties of the catalyst. In particular, the strength and abrasion resistance of the catalyst become more critical, because the catalyst particles suffer more wear and tear by colliding with each other and with the walls of the unit. In consequence, the conventional extrusion-shaped catalyst particles are less suitable for use in non-fixed bed processes, because these particles have corners that may easily wear down in these applications. Further, because the catalyst is continuously or intermittently fed to or removed from the reactor, it must have such a form as to allow easy flowing and transfer as a slurry containing the reacting substances.
Therefore, there is a continuing need for hydroprocessing catalysts which are suitable for use in fixed bed applications, but in particular in non-fixed bed applications, which show a high hydroprocessing activity in the hydroprocessing of heavy hydrocarbon feeds, in particular for effecting simultaneous hydrodemetallization and hydrodesulfurization of such feeds, in combination with a high abrasion resistance and a long life. The present invention provides such a catalyst.
In one embodiment the present invention is directed to a spherical catalyst composition comprising a Group VI metal component and optionally a Group VIII metal component on a carrier, which catalyst has a particle size of 0.5-7 mm, a total pore volume of 0.5-1.3 ml/g, an average pore diameter of 15-30 nm, and a % PV( greater than 100 nm) of 2-30%, there being substantially no difference in density between the core region of the carrier particles and their surface regions.
In a second embodiment, the present invention comprises a spherical catalyst carrier, which has a particle size of 0.5-7 mm, a total pore volume of 0.5-1.3 ml/g, an average pore diameter of 15-30 nm, and a % PV( greater than 100 nm) of 2-30%, there being substantially no difference in density between the core region of the carrier particles and their surface regions.
Other embodiments of the invention encompass details about the making of the spheres, the properties of the spherical oxide particles, metal components of the hydroprocessing catalyst and the use of the catalyst in a process for the hydroprocessing of a hydrocarbon feed, etc., all of which are hereinafter disclosed in the following discussion of each of the facets of the present invention.